Study on N-guanylurea-dinitramide (GUDN) decomposition using theoretical simulations, online photoionization mass spectrometry and TG-DSC-IR-MS experiments

Abstract

Abstract N-guanylurea-dinitramide (GUDN) has received widespread attention due to its high energy and low sensitivity. Research on thermal decomposition behavior of energetic materials plays an important role in their practical application. However, determining transition state products from an experimental technology remains a question to be solved. Herein, theoretical calculations (ReaxFF reactive molecular dynamics and DFT calculations) coupled with online photoionization mass spectrometry and TG-DSC-IR-MS were performed to elucidate the thermal decomposition mechanism of GUDN. The infrared peak evolution of condensed phase products is investigated by in situ IR spectroscopy. Molecular dynamics, DFT calculations and in situ IR results suggest that the first step of GUDN unimolecular decomposition is hydrogen transfer reaction, followed by the reaction between two amino groups on the hydrogen transfer product of guanylurea to lose NH3, and then the remaining structure break from the C N bond and finally decomposed into NCO and CN2H3 fragments. The major products of GUDN decomposition include CO2, N2, H2N2 and NH3, and the minor products are H2O and HN2. The products NO2, NO, and CO only participate in initial formation and intermediate conversion reactions. This work is helpful for understanding the entire decomposition process of GUDN with theoretical calculations and experimental methods.